This invention relates to a fuel injection system for an engine and more particularly to an improved fuel injection system and combustion chamber configuration that permits good combustion efficiency under all running conditions and particularly at idle and low speed conditions.
It is readily realized that the combustion efficiency, fuel economy and exhaust emission control for an engine can be improved through the expediency of using direct cylinder fuel injection. The advantages of direct cylinder injection are particularly advantageous in two-cycle engines. However, when direct cylinder fuel injection is employed, the amount of fuel injected at idle and low speed conditions is quite small. Therefore, it is important to insure that there is a stoichiometric mixture present at the gap of the spark plug at the time the plug is fired under these running conditions. Although various arrangements have been proposed to assure this, none of the systems have been completely effective.
It is, therefore, a principal object of this invention to provide a fuel injection system for an engine wherein it will be insured that the charge is fired under all running conditions and particularly under idle.
It is a further object of this invention to provide an improved combustion chamber and fuel injection system for an engine that will insure rapid flame propagation under all running conditions and particularly under idle.
In addition to insuring that the charge is effectively ignited under all conditions and particularly idle, it is also desirable to insure that the flame propagation is very rapid. It has been found that one of the principle difficulties with maintaining good idle running is the normally slow flame propagation that results under this condition.
It is, therefore, a further object of this invention to provide an improved injection and combustion chamber system for an engine that will insure rapid flame propagation at idle.
In conjunction with the ignition system for internal combustion engines, it has been proposed to employ two spark plugs per combustion chamber. Normally two spark plugs are employed so that it will be insured that the flame propagates completely across the combustion chamber under all conditions. That is, it is the conventional practice to position the two spark plugs at spaced locations within the combustion chamber and wherein each initiates a flame front which will join and insure complete combustion. However, it has been discovered that by positioning two spark plugs in the same general area of the combustion chamber but at slightly spaced locations relative to each other it can be insured that a small, partially stratified, charge can be ignited under all conditions. It is, therefore, a further object of this invention to provide such an arrangement.